Following Christine O'Donnell's surprising upset victory over Congressman Mike Castle, I learned that in the last days before the primary election, Ms. O'Donnell's former campaign manager, Kristin Murray, made robocalls informing voters that Ms. O'Donnell "was living on campaign donations -- using them for rent and personal expenses, while leaving her workers unpaid and piling up thousands in debt."

I also spoke to former campaign staff member David Keegan, who made similar comments and provided details. As a former prosecutor heading up an organization that focuses on money and politics, I realized Ms. O'Donnell had embezzled campaign funds to support herself.

As a result, my organization, Citizens for Responsibility and Ethics in Washington (CREW) quickly filed a complaint with the Federal Election Commission (FEC) and asked the Delaware U.S. Attorney's Office to open a criminal investigation.

Did Ms. O'Donnell respond by publicly justifying her expenditures to the media and the public? Did she explain how she had managed to eat and pay rent on the mere $5,800 income she disclosed for 2009?

No. Instead, while decrying Washington, she left it to her newly hired expensive Washington lawyer (finally, a legitimate campaign expense!), well-known Republican insider Cleta Mitchell, not to defend her conduct, but to mount an attack against CREW.

Ms. Mitchell threatened to sue CREW for libel, while in the same breath, lying about CREW's record, calling us a Democratic front group. Clearly, Ms. Mitchell hoped to change the subject from Ms. O'Donnell's conduct to CREW's. But don't expect a lawsuit; truth is a defense to a libel claim.

As Ms. O'Donnell's former staff members reported, she used tens of thousands of dollars from her campaign to finance her personal life. For example, in March and April 2009, Ms. O'Donnell paid her rent out of her campaign account, but called the payments expense reimbursements.

She also claimed other personal expenses, such as meals, gas and even a bowling outing, were campaign related.

In addition, Ms. O'Donnell, who had no campaign treasurer, personally filed in the reports she submitted to the FEC. Without any oversight, it was easy for her to file reports falsely claiming expenditures for rent, meals and the like were campaign related. Knowingly filing false reports with the FEC is a federal crime.

Finally, by treating campaign funds like her own money, those funds became income and like all other income, should have been reported to the IRS. But given that Ms. O'Donnell lied on her FEC forms, it is highly unlikely she declared this income on her tax returns meaning she likely committed a third crime: tax evasion.

If Ms. O'Donnell were to sue CREW for libel, the court would allow us to prove we had told the truth. We would be granted the right to depose witnesses under oath, including not just former campaign staffers such as Mr. Keegan and Ms. Murray, as well as Ms. O'Donnell's four former campaign treasurers, but also Ms. O'Donnell herself. We would have the chance to ask detailed questions about how Ms. O'Donnell supported herself on just $5,800, and we could question and demand records and receipts for each so-called campaign expenditure. And of course, CREW would be free to make all of that information public.

No lawyer, not even one as poorly versed in libel law as Ms. Mitchell appears to be, would put her aspiring political candidate through that. So a lawsuit is probably not forthcoming.

Ms. Mitchell also has stated that Ms. O'Donnell will go back and "correct" FEC forms that might have "mistakenly" listed expenses incorrectly. Further, Ms. Mitchell has suggested Ms. O'Donnell will retroactively take a salary from the campaign, which would make the rent payments permissible. If this sounds legally dubious, that's because it is.

While candidates legally can collect a salary from their campaign, they can't do so retroactively. Just like a bank robber can't go back in time and claim the stolen money was actually a "security consulting fee," Ms. O'Donnell can't turn back the clock either.

Ms. O'Donnell would prefer Delawareans focus not on her actions, but on CREW's motives. First, CREW is a nonpartisan organization with a long record of taking on unethical politicians regardless of party affiliation. But more important, Christine O'Donnell is running to serve the people of Delaware as their elected representative in the United States Senate -- a position that demands integrity and honesty.